In the chemical and energy providing industries there is a great demand for gas containing substantial amounts of hydrogen and/or carbon monoxide in various mixtures and purities. Such gas may be used, for instance, as a starting material for the manufacture of chemical products -- e.g., ammonia, alcohols, etc., -- as a reducing agent, as a clean fuel or in hydrogenation processes. A well-known and widely employed method for the preparation of such a gas is the partial combustion of hydrocarbonaceous fuels in a substantially void or hollow reactor. One of the attractive aspects of this process is its flexibility in the types of hydrocarbon fuels which can be converted to the desired gaseous products. Suitable hydrocarbonaceous fuels which may be subject to partial combustion in this non-catalytic process include normally gaseous and liquid hydrocarbons, e.g., middle distillates and light and heavy fuel oil, as well as liquid fuels mixed with solid carbon-containing particles such as the carbon soot typically obtained as a product of partial combustion. The combustion can be effected with oxygen, with air, or with air which has been enriched with oxygen. Frequently steam is added to the reaction mixture.
A frequently used hydrocarbonaceous fuel is a residual petroleum fraction which fuel contains ash-forming constituents. However, the percentage of ash is relatively low, i.e., generally not exceeding 0.05% weight, and in the conventional hollow reactors such an ash content presents no difficulties. The ash particles thus formed leave the reactor with the product gases and are separated from the gases by means known in the art, before, after or during cooling of the gases.
However, some hydrocarbonaceous fuels employed contain more than about 0.1%w finely dispersed solids. Liquid petroleum fractions with a far higher content of finely dispersed solids is obtained, for instance, from the mining and processing of tar sands. These tar sand deposits occur in very large deposits at various places on earth and present potentially valuable sources of petroleum. Dependent on the process employed to extract the petroleum from the tar sands, liquid petroleum fractions are obtained with a solids content varying typically from about 0.5 to about 5.0% weight. These solids consist mainly of sand and clay particles.
Another source of high solid content hydrocarbonaceous fuel employed in partial combustion processes is a liquid petroleum fraction containing a dispersion of coal, soot or coke. The coal may be hard coal, such as anthracite, or bituminous coal, brown coal or lignite. Such dispersions of solid particles in liquid petroleum fractions are useful fuels in partial combustion processes because it is a convenient means of pressurizing solid fuel in a reactor in order to gasify the solid and liquid fuel. The solid particles, in particular the various type of coal, typically contain ash-forming constituents.
It has now been found that employing such liquid petroluem fractions containing finely dispersed solids as feed to a partial combustion process results in the formation of deposits in the reactor, in particular on the wall opposite the fuel inlet, and in such amounts that normal operation must regularly be interrupted for removing such deposits from the reactor walls.